I *think* the author is trying to say that bitcoin cannot grow due to the fact that if it will, the incentive to do a 51% attack would become too big.
To counter this his argument is that the transaction value of each block must be atleast X amount of $, ( to make it unprofitable to do such an attack, (Right?)), which means that relative small transactions will become impossible, ( due to the high fees and limited blocks) and thus bitcoin would never "work" on a larger scale/be adopted due to the fact that there are much better/cheaper options out there.
But if you increase the value to $, then the gains from the attack would similarly increase dollar value. So as long as the Bitcoin value is profitable, the attack will always be profitable at any price, I would assume.
I've read the thread but not the paper, and I have one immediate and relevant comment.
The peer review process of that paper is quite obviously THIS THREAD.
It is not the various "experts" to whom the paper was sent for peer review.
Various errors and questions have been raised in this thread. I'll try to have a comment in a couple of days that's more than just a quickie.
Now that you point this out, I wonder when all these experts will realise this and actually come here on this forum seeking peer review. If you think about it too, a lot of the so-called peer reviewing done in academic research is self-serving. To be cynical, having this forum's experts probably disqualifies peer review since they're probably a lot more competent than the academicians typically doing these reviews (peer reviewers generally should be those of similar competence

).